Arrhythmias in Real Life Course, Khartoum, Sudan, August 2014

1. Bradycardias
Salah Abusin, MD, MRCP, ABIM, ABIM (Card)
Interventional Cardiologist
Dubuque, IA, USA

2. Bradycardias
• SA node dysfunction or
Sick Sinus Syndrome
– Inappropriate sinus
bradycardia
– Sinoatrial exit Block
– Sinus Pause/Arrest
– Tachycarda/Bradycardia
syndrome
– Persistent Atrial Standstill
• AV Blocks
– First Degree
– Second Degree
• Mobitz I
• Mobitz II
• 2:1 Block
– Third Degree
– High Grade AV Block

4. Sinoatrial Node dysfunction
• Inappropriate sinus bradycardia
• Sinoatrial exit Block
• Sinus Pause/Arrest
• Tachycarda/Bradycardia syndrome

5. Causes - Intrinsic
• Idiopathic degenerative disease
• Coronary Artery Disease
• Cardiomyopathy
• Hypertension
• Infiltrative Disorders (amyloidosis etc..)
• Collagen Vascular Disorders (scleroderma etc.)
• Inflammatory Processes (myocarditis)
• Surgical Trauma
• Musculoskeletal disorders (myotonic dystrophy)
• Congenital heart disease (postoperative or
absence of correction)

6. Causes – Extrinsic - 1
• Medication
– BBs, CCBs, digoxin
– Clonidine, alpha methyldopa, reserpine
– Antiarrhythmics Type
• IA (quinidine, procainamide)
• IC (flecainide)
• III (amiodarone)
– Lithium

7. Causes – Extrinsic - 2
• Autonomic influences
– High vagal tone
– Carotid sinus syndrome
– Vasovagal syncope
• Electrolyte abnormalities
– Hyperkalemia, hypercarbia, hypothyroidism
• Increase intracranial pressure
• Hypothermia
• Sepsis

8. Sinoatrial Node dysfunction
• Inappropriate sinus bradycardia
• Sinus Pause/Arrest
• Sinoatrial exit Block
• Tachycarda/Bradycardia syndrome

9. Inappropriate Sinus Bradycardia
Chronotropic Incompetence
• HR<60 that doesn’t increase appropriately with
exercise
• Usually defined as failure to attain 80% of
maximal age predicted HR (MAHR) on exercise
testing
• MAHR = 220 – Age
• e.g. failure to reach a HR of 120 in a 70 year old
patient

10. Sinus bradycardia

11. Sinoatrial Node dysfunction
• Inappropriate sinus bradycardia
• Sinus Pause/Arrest
• Sinoatrial exit Block
• Tachycarda/Bradycardia syndrome

12. Sinus Pause/Arrest
• Defined as absence of a sinus beat for >=3
seconds while AWAKE
• SA node fails to discharge so no atrial activity
occurs

13. Sinus Pause/Arrest

14. Sinoatrial Node dysfunction
• Inappropriate sinus bradycardia
• Sinus Pause/Arrest
• Sinoatrial exit Block
• Tachycarda/Bradycardia syndrome

15. Sinoatrial Exit Block
• SA node discharges an impulse that does NOT
result in atrial activity

16. Sinoatrial Exit Block

17. Sinoatrial Node dysfunction
• Inappropriate sinus bradycardia
• Sinus Pause/Arrest
• Sinoatrial exit Block
• Tachycarda/Bradycardia syndrome

18. Tachycardia-Bradycardia Syndrome
• Bradycardia/sinus pauses interspersed with
atrial arrhythmias (AFL, A fib, A tach)
• Sinus arrest manifests after termination of
atrial arrhythmia (spontaneously or after DCCV)
• Sinus Node Recovery Time (SNRT) uses the
above observation to assess SA node function
in EP studies

19. Tachycardia-Bradycardia Syndrome
Hurst the Heart
12th
Edition

20. Indications for pacing in SND
• Class I (recommended)
– SND with documented symptoms
– SND due to irreversible factors or due to essential
drug therapy
– Chronotropic incompetence
• Class III (NOT recommended)
– Asymptomatic

21. Bradycardias
• SA node dysfunction or
Sick Sinus Syndrome
– Inappropriate sinus
bradycardia
– Sinoatrial exit Block
– Sinus Pause/Arrest
– Tachycarda/Bradycardia
syndrome
– Persistent Atrial Standstill
• AV Blocks
– First Degree
– Second Degree
• Mobitz I
• Mobitz II
• 2:1 Block
– Third Degree
– High Grade AV Block

22. AV Blocks
• First Degree
• Second Degree
– Mobitz I
– 2:1 Block
– Mobitz II
• Third Degree
• High Grade AV Block

23. First Degree AV Block
• PR interval > 200msec
• If QRS is normal, block is usually at the level of
the AV node
• If QRS shows bundle branch block, block
maybe in His-Purkinje System

24. First degree AV block

25. Management
• Usually no specific therapy is required

26. Second Degree Heart Block
Mobitz I or Wenchebach
• Progressive Prolongation of the PR interval
and shortening of the RR interval until a P
wave is blocked
• RR interval containing the non conducted P
wave is less than two PP intervals
• PR interval longer after the non conducted P
wave
• Grouped beating

27. Second Degree – Mobitz I
P P P P P P

28. Causes
• Normal
• Athletes
• Medications
• Myocardial Infarction
(inferior wall)
• Acute rheumatic fever
• Myocarditis
Features
• Usually asymptomatic
• Usually narrow QRS complex
 block at AV node
• The presence of bundle branch
block suggests the possibility
of block below the AV node in
His Purkinje system

29. Management
• Usually do not require permanent pacing

30. Second Degree – Mobitz II
• Constant PR interval with intermittent
nonconducted P wave and no evidence for PACs
• RR interval between non conducted P waves is
equal to two PP intervals
• Each QRS is preceded by multiple P waves
• 3:1, 4:1 also called high grade AV block
• Other variations include 3:2
• 2:1 block maybe Mobitz I or Mobitz II

31. High Grade AV Block

32. PP PP
Second Degree Heart Block
2:1 Block

33. Management
• Usually require permanent pacing especially if
symptomatic due to high likelihood of
progression to high grade AV block and third
degree AV block

34. Differentiating mechanism of 2:1 block
Feature Mobitz I Mobitz II
QRS duration Narrow Wide
Response to increasing
HR & AV conduction i.e.
exercise, atropine
Improves Worsens
Response to decreasing
HR & AV conduction i.e.
carotid sinus massage
Worsens Improves
Acute MI Inferior Anterior

35. Third Degree AV block
• Atrial impulses consistently fail to reach the
ventricles, resulting in atrial and ventricular
rhythms that are independent of each other
• PR interval varies
• PP and RR intervals are constant
• Ventriculophasic sinus arrhythmia
– PP interval containing QRS is shorter than PP
interval without a QRS complex

36. Third Degree AV block
P P P P P P P P P PP

37. Escape Rhythms
• Junctional
– Usually narrow (may be wide if underlying BBB)
– 40-60/min
• Ventricular Escape Rhythm
– Wide complex
– 30-40/min (range 20-50)

38. Causes
• Myocardial Infarction
– Inferior wall, usually transient, associated with a
stable junctional escape rhythm
– Anterior wall, usually permanent
• Degenerative Disease
• Infiltrative Disease (amyloid, sarcoid)
• Endocarditis (Aortic Root abscess)
• Hyperkalemia
• Medication
• Post Cardiac Surgery

39. Management
• Usually require permanent pacing

40. Acclerated Idioventricular rhythm

41. Acclerated Idioventricular rhythm
• Regular Wide complex rhythm
• 60-110/min
• AV dissociation
• Benign phenomenon
• Causes
– Normal
– Coronary reperfusion
– Digoxin toxicity

42. Problems

43. 3rd
degree AV block, junctional escape

44. Second Degree Mobitz I

45. P P P P P P P P P P P
3rd
degree AV block, junctional escape

46. P P P P P P P P P P
3rd
degree AV block, junctional escape
or high grade AV block

47. Problem
• 50 year old female with no PMH presents with
acute onset of shortness of breath on exertion
of 4 days duration
• HR 50/min, BP 140/80
• Initial ECG sinus bradycardia
• TropI 1.2

48. Sinus arrest with ventricular escape

49. Sinus arrhythmia

50. Problem
• 65 year old male presented with 4 day history
of shortness of breath on exertion, orthopnea
and PND
• HR 50/min, regular, BP 150/70

51. Atrial Fibrillation with 3rd
degree AV
block & junctional escape

52. Single Chamber Ventricular Pacing at
45/min with complete heart block

53. Dual Chamber Pacing with marked
anterolateral ST depression

55. Sick Sinus Syndrome
Sinus pauses with interspersed short runs
of Atrial Fibrillation

56. Thank You